Method of and apparatus for testing monitoring organs in a turbine installation

ABSTRACT

Two sets of speed and pressure monitoring organs are located respectively in two safety systems normally operated in parallel and independently of each other for protecting a turbine against overspeed and also against overpressure in a unit such as a water separator or the like located in the gas flow path. In order to test the monitoring organs of both systems for determining whether or not they would function properly in the event of an actual overspeed or overpressure condition, one of the safety systems is taken out of service while the other continues to monitor actual turbine speed and pressure, and vice versa, and the speed and pressure monitoring organs of the safety system removed from service are then tested by introducing test speed and pressure values.

United States Patent [1 1 Kalverboer METHOD OF AND APPARATUS FOR TESTINGMONITORING ORGANS IN A TURBINE INSTALLATION [75] Inventor: CornelisKalverboer, Nussbaumen,

Switzerland [73} Assignee: Aktiengesellschaft Brown, Boveri &

' Cie, Baden, Switzerland [22] Filed: Mar. 23, 1971 [21] Appl. N0.:127,246

[30] Foreign Application Priority Data [111 3,744,311 [451 July10, 19733,429,180 2/1969 Vind 73/168 Primary Examiner-Richard C. QueisserAssistant Examiner-Denis E. Corr Attorney-Pierce, Scheffler & Parker 5 7ABSTRACT Two sets of speed and pressure monitoring organs are locatedrespectively in two safety systems normally operated in parallel andindependently of each other for protecting a turbine against overspeedand also against overpressure in a unit such as a water separator or thelike located in the gas flow path. In order to test the monitoringorgans of both systems for determining whether or not they wouldfunction properly in the event of an actual overspeed or overpressurecondition, one of the safety systems is taken out of service while theother continues to monitor actual turbine speed and pressure, and viceversa, and the speed and pressure monitoring organs of the safety systemremoved from service are then tested by introducing test speed andpressure values.

6 Claims, 1 Drawing Figure METHOD OF AND APPARATUS FOR TESTINGMONITORING ORGANS IN A TURBINE INSTALLATION The present inventionrelates to an improved method for testing monitoring organs in a turbineinstallation against overspeed of the turbine and also againstoverpressuring in a tank such as that housing a water separator,superheater or the like in the intermediate steam line thereof by twomutually independent safety systems for the control of hydraulicallyand/or electromagnetically operated valves, each of the safety systemsbeing controlled as a function of a speed monitor and simultaneously ofa pressure monitor uncoupled from the speed monitor, and an apparatusfor carrying out this method.

The arrangement of pressure tanks in thermal power installations, inparticular between the individual working stages of a turbineinstallation, brings up the necessity of protecting such tanks fromundue overpressure. In thermal power installations,for example, withboiling water reactors as a heating arrangement, such tanks are eitherwater separators or superheaters located between the high-pressuresection and the low-pressure section of a steam turbine.

Protection of a tank against overpressure is one of the primary tasksexacted by the government authorities. With the development of safetydevices and the ever stricter regulation it has become necessary to beable to check this device for its effectiveness. Especially in thedevelopment of radioactively radiating or radioactively operated powerplant installations, this factor should be applied more stringently.

The problem underlying the present invention is to test the mutuallyindependent control systems for the protection of the tank againstoverpressure during operation without having to throttle the steamturbine installation in its output or even turning it off, while at thesame time maintaining the safety and control systems of the steamturbine and of the tank.

According to the invention, this problem is solved in that one of thesafety systems controlling the monitoring organs against overpressure isconnected to a testing system operated independently of the safetysystems, which testing system is controllable hydraulically and/orelectromagnetically, whereby the pressure and speed monitors are checkedfor their effectiveness, and that the parallel existing second systemcarries out the safety regulation of the turbine installation during thechecking of the monitoring organs of the first safety system.

A device for carrying out the method is characterized by a testingsystem connected to parallel-connected safety systems of the monitoringorgans and consisting of a separating valve operable by control relaysand valves, which valve is connected directly with the safety systems,and consisting of a pressure testing system of higher pressure levelthan that of the intermediate steam line which can be connected in thetesting state.

The advantages of the invention result from the continuous monitoring ofthe pressure tank during operation, double safety being assured at alltimes, since even when the monitoring or control organs of one safetysystem are being checked, the controllability and supervision of thepower plant installation is maintained.

The advantage resulting from the double safety system and control theelimination of break plates,

safety valves and the respective lines on pressure tanks endangered byover-pressure is welcomed both from a standpoint of economic, as well astechnics since, on the one hand, the production costs can be greatlyreduced and, on the other hand the previously restricted spaceconditions can be improved.

In boiling water reactors, the steam carries with itradioactive-radiation particles and must therefore not be dischargedinto the atmosphere. For this reason it is of advantage to employexisting monitoring systems with the testing method, as thereby aletting off of the steam can be avoided completely. Thus, also thedanger of radioactive pollution is banned.

The invention will be further explained with reference to theaccompanying drawing, the single view of which presents in a somewhatdiagrammatic manner an example of construction of the double safetysystem and of the test circuits connected thereto.

A heating device 1, which represents, for example, a boiling waterreactor, is connected via a fresh steam line 2 with the high-pressuresection 3 of the turbine. The exhaust steam of the high-pressure stage 3is supplied via the intermediate steam line 4 to the lowerpressure stage5 of the turbine. Through line 1 1 exhaust steam from the low pressurestage 5 is introduced into the condenser 12, after which the condensateis returnable to the reactor 1 for reheating. On an extended part of theturbine shaft 7, which is indicated symbolically by a dash-dot doubleline 10, there are disposed two speed monitors 8 and 9.

Located in the intermediate steam line 4 between the high and lowpressure turbine sections is a water separator 6 which is to beprotected against internal overpressure. For carrying out the protectivemeasures there are provided a rapid-closing valve 14 in the fresh steamline 2 and a rapid-closing valve 13 in the intermediate steam line 4,both rapid-closing valves 13, 14 being supplied with pressurized oil vialine 15. The pressurized oil is admitted through line 18 from a suitablepressurizing source and can flow off again through line 19 to a returnsump.

For pressureless control or respectively for the closing of valves 13,14, by their loading springs, a flow restrictor 16 is lodged in thepressure medium supply line 18, on the one hand and a spring loaded,fluid actuated control valve 17 is placed in the pressure mediumdischarge line 19, on the other hand. For actuating the control valve 17to a more closed position, it is connected via fluid pressurized line 20with the safety system 21a and also with the safety system 21b, whichare connected in parallel. The safety systems 21a, 21b are provided withpressurized oil feed lines 22a and 22b, in which flow restrictors 34a,34b for adjustment of the pressure are arranged.

The subscripts of the reference symbols mentioned in the description andin the drawing are arranged so that like subscripts are correlated withthe safety system 21a, 21b marked with the same subscript. An exceptionwas made only with the deviceto be tested (pressure monitor or speedregulator), to make clear the different functions.

The two safety systems 21a, 21b are subsequently connected with thepressure monitor 24 or 25 correlated with 'a safety system, namely, viathe blocking valves 26a and 26b controllable independently, of thepressure monitors, which valves are lodged respectively in the lines ofthe safety systems 21a, 21b.

Another connection exists from the individual parallel-connected safetysystems 21a, 21b to the speed monitors 8 and 9 via the blocking valves33a and 33b which are controllable as a function of these monitors andare arranged also for controlling the safety systems 21a, 21b in theoutflow lines 23.

The pressure monitors 24, 25 are connected,'besides the connection withthe safety systems 21a, 21b, via the monitoring lines 27a, 27b 27 to theintermediate steam line 4. It is thereby possible to monitorcontinuously the steam pressure prevailing in the intermediate steamline 4. To be able to effect a testing of the pressure monitors 24, 25,however, it is necessary to bring the pressure monitors 24, 25 intoconnection with a system of higher pressure 32. For this purpose flowrestrictors 29a and 29b are installed in the pressure monitoring lines27a, 27b, which restrictors permit a pressure build-up largelyindependent of the intermediate steam between the pressure monitors 24and 25 and two other restrictors 28a or 28b, which are locatedrespectively in branch lines 31a, 31b connected with line 32 of thehigher pressure level system provided. Mechanically or hydraulicallyactuatable cut-off valves 30a, 30b are located respectively in thebranch lines 31a, 31b which permit selective connection to ordisconnection of the higher pressure level system 32 from the pressuremonitors 24, 25.

With this device it is now possible to check the pressure monitors 24,25 selectively for their effectiveness without having to effect adisconnection of the monitoring or of the safety system. The checking ofthe speed monitors 8 and 9 is done in the conventional manner, whichneed not be described in detail as it is continuously used.

During normal operation, the two safety systems 21a, 21b operate inparallel to provide double protection. System 210 monitors turbine shaftspeed and pressure in the intermediate steam line 4 by means of theoverspeed and pressure monitors 8 and 24, and the other system 21blikewise monitors turbine shaft overspeed and the pressure in steam line4 by means of the speed and pressure monitors 9 and 25. In order to beable to test the overspeed and pressure monitors in each of the twosafety systems, it is necessary to temporarily separate the two safetysystems so that system 21a can be tested while the other system 21bremains in operation, and vice versa. This is effected by means of acompound slide valve assembly 43 which includes one cutoff valve member41a correlated to safety system 21a, and another cut-off valve member41b correlated to safety system 21b. The two valve members 41a, 41b aremechanically interconnected by means ofa rod 40, and they are actuatablehydraulically and conjointly by means of spring loaded pistons 42a, 42b.When both of the pistons 42a, 42b are subjected to the same fluidpressure, the resultant forces applied by the fluid, acting in oppositedirections, respectively on these pistons,

.serve to maintain the valve members 41a, 41b in a central, valve-openposition, and the respective fluid pressures of the two safety systems21a, 21b are put through in parallel to control line leading to thesafety cutoff valve 17. Should per chance neither of the pistons 42a,42b be subjected to hydraulic pressure, the loading springs associatedtherewith will serve to also maintain the valve members 41a, 41b in acentral, balanced position such that both of the valves are open and therespective fluid pressures of the safety systems 21a, 21b are putthrough in parallel to the control line 20.

The cut-off valve 41a is controlled by an auxiliary pressurized line 35aleading to piston 42a through a valve 360 controlled by a relay 39awhich can be of the electromagnetic type. Another valve 37a alsocontrolled by relay 39a is located in a return-to-sump iine 38a, thearrangement being that when relay 39a is actuated, valve 36a closes andvalve 370 opens thus relieving piston 42a of pressure and permitting thepressure existing on piston 42b to move the cut-off valve 41a via therod 40 to its closed position thus isolating safety system 210 from line20. The safety system 21b remains in operation since when valve 41acloses, the other valve 41b merely moves to a more open position as aresult of the movement of piston 42b.

In a similar manner, cut-off valve 41b is controlled through auxiliarypressurized line 35b leading to piston 42b through valve 36b controlledby electromagnetic relay 39b, and another valve 37b also controlled byrelay 39b is located in return-to-sump line 38b. When relay 39b isactuated, piston 42b is thus relieved of pressure thus causing cut-offvalve 41b to shift to its closed position by the pressure remaining onpiston 42a and isolate safety system 21b from line 20 while the othersafety system 210 remains in its normal operating state to monitorpressure at the tank of water separator 6 and the turbine overspeed.

The process for the testing of the pressure monitors 24, 25 andoverspeed monitors 8 and 9 will now be described in its various steps.

To test the safety system 21a, control relay 39a is energized thus tocause valve 41a to be displaced unti line 20 is separated from thesafety system 21a. Then the overspeed monitor 8, which is connected tothe separated safety system 21a, is checked for its effectiveness inthat the mass of the centrifugal weights on the monitor is increasedcontinuously until the blocking valve 33a responds and clears thedischarge 23.

For the testing of the pressure monitor 24, the cut-off valve 30 isgradually opened, so that it becomes possible to supply the pressuremedium of higher level to the pressure monitor 24. The valve 30a isopened until the pressure reaches a magnitude at which the pressuremonitor 24 responds and the blocking valve 26a opens; hence, themonitoring organ transmits a signal which would be indicative of adangerously high pressure within the water separator 6.

The testing of the safety system 21a can be terminated in a simplemanner by closing the valve 300, the pressure monitor 24 thentransmitting to the blocking valve 26a its command to block the outflowline 23. Relay 39 is then restored to its initial position thuseffecting a build-up of pressure in the pressure line 35a, whereuponvalve 41a is restored to its rest i.e. its open position, whereby thetesting for system 21a is completely turned off. All during the testingof safety system 21a, the other safety system 21b remains in service.The safety system 21b is tested by the same process by actuating 41b toits closed position, whereupon the process repeats in the same sequenceof steps, the other safety system 210 being unaffected and continuing tomonitor overspeed and pressure.

I claim:

1. In a gaseous fluid turbine system, the combination comprising a pairof safety systems normally operated in parallel and independently ofeach other and which are connected into the turbine system to protectthe turbine against overspeed and also against an overpressure in thepath of the gas flow through the turbine system, each said systemincluding an overspeed monitor responsive to turbine shafet speed and apressure monitor responsive to pressure in said gas flow path, meansresponsive to either monitor of either safety system for shutting offthe gas flow to the turbine, and means for selectively taking each oneof said safety systems out of service while the other safety systemcontinuesto perform its monitoring functions in order to test theoperability of the monitors of the safety system taken out of service.

2. A turbine system as defined in claim 1 wherein each of the two safetysystems operating in parallel is of the pressurized fluid type and aresponse of either the speed or pressure monitor serves to de-pressurizethe system, and wherein said means for selectively taking one of saidsystems out of operation while the other system continues to perform itsmonitoring function comprises selectively operable valve means fordisconnecting one or the other of said pressurized fluid safety systemsfrom said monitor responsive gas flow shut-off means.

3. A turbine system as defined in claim 2 wherein said selectivelyoperable valve means for disconnecting one or the other of saidpressurized fluid safety systems is constituted by a compound slidevalve, said slide valve including mechanically coupled valve membersrespectively correlated to said safety systems and which normally are intheir open position, and means for selectively actuating said valvemembers such that as one valve member moves in a closing direction theother valve member moves in a non-closing direction.

4. A turbine system as defined in claim 1 which further includes anauxiliary pressure source for testing said pressure monitors, whereineach of the two safety systems operating in parallel is of thepressurized fluid type and a response of either the peed or pressuremonitor serves to depressurize the system, wherein said means forselectively taking one of said systems out of operation while the othersystem continues to perform its monitoring function comprisesselectively operable valve means for disconnecting one or the other ofsaid pressurized fluid safety systems from said monitor responsive meanswhich serves to shut off gas flow to said turbine, and wherein forselective testing of said pressure monitors valve means are provided forapplying said auxiliary pressure to said pressure monitors on aprogressively increasing basis.

5. A gaseous fluid turbine system as defined in claim 1 and whichfurther includes an auxiliary pressure source providing a test pressurehigher than that of the normal pressure conditions existing in saidturbine system, and means connecting said auxiliary pressure source intoeach of said pressure monitors.

6. In the method for testing each of two safety systems including speedand pressure monitors connected into a turbine system and which systemsare normally operated in parallel and independent of each other forprotecting the turbine against overspeed and also against anyoverpressure in the path of the gas flow through the turbine system, thesteps which include taking the first one of said safety systems out ofservice while the second safety system continues to provide itsmonitoring functions, testing the operability of the speed monitor ofsaid first safety system and testing the operability of the gas fiowpressure monitor of said first safety system by application of aprogressively variable pressure thereto from an auxiliary source ofpressure higher than that of the normal pressure conditions existing insaid turbine system, restoring said first safety system to service,taking said second safety system out of service while said first safetysystem continues to provide its monitoring functions, testing theoperability of the speed monitor of said second safety system andtesting the operability of the gas flow pressure monitor of said secondsafety system by application of a progressively variable pressurethereto from said auxiliary source of pressure higher than that of thenormal pressure conditions existing in said turbine installation, andfinally restoring said second safety system to service operation inparallel with said first safety system.

1. In a gaseous fluid turbine system, the combination comprising a pairof safety systems normally operated in parallel and independently ofeach other and which are connected into the turbine system to protectthe turbine against overspeed and also against an overpressure in thepath of the gas flow through the turbine system, each said systemincluding an overspeed monitor responsive to turbine shafet speed and apressure monitor responsive to pressure in saiD gas flow path, meansresponsive to either monitor of either safety system for shutting offthe gas flow to the turbine, and means for selectively taking each oneof said safety systems out of service while the other safety systemcontinuesto perform its monitoring functions in order to test theoperability of the monitors of the safety system taken out of service.2. A turbine system as defined in claim 1 wherein each of the two safetysystems operating in parallel is of the pressurized fluid type and aresponse of either the speed or pressure monitor serves to de-pressurizethe system, and wherein said means for selectively taking one of saidsystems out of operation while the other system continues to perform itsmonitoring function comprises selectively operable valve means fordisconnecting one or the other of said pressurized fluid safety systemsfrom said monitor responsive gas flow shut-off means.
 3. A turbinesystem as defined in claim 2 wherein said selectively operable valvemeans for disconnecting one or the other of said pressurized fluidsafety systems is constituted by a compound slide valve, said slidevalve including mechanically coupled valve members respectivelycorrelated to said safety systems and which normally are in their openposition, and means for selectively actuating said valve members suchthat as one valve member moves in a closing direction the other valvemember moves in a non-closing direction.
 4. A turbine system as definedin claim 1 which further includes an auxiliary pressure source fortesting said pressure monitors, wherein each of the two safety systemsoperating in parallel is of the pressurized fluid type and a response ofeither the peed or pressure monitor serves to depressurize the system,wherein said means for selectively taking one of said systems out ofoperation while the other system continues to perform its monitoringfunction comprises selectively operable valve means for disconnectingone or the other of said pressurized fluid safety systems from saidmonitor responsive means which serves to shut off gas flow to saidturbine, and wherein for selective testing of said pressure monitorsvalve means are provided for applying said auxiliary pressure to saidpressure monitors on a progressively increasing basis.
 5. A gaseousfluid turbine system as defined in claim 1 and which further includes anauxiliary pressure source providing a test pressure higher than that ofthe normal pressure conditions existing in said turbine system, andmeans connecting said auxiliary pressure source into each of saidpressure monitors.
 6. In the method for testing each of two safetysystems including speed and pressure monitors connected into a turbinesystem and which systems are normally operated in parallel andindependent of each other for protecting the turbine against overspeedand also against any overpressure in the path of the gas flow throughthe turbine system, the steps which include taking the first one of saidsafety systems out of service while the second safety system continuesto provide its monitoring functions, testing the operability of thespeed monitor of said first safety system and testing the operability ofthe gas flow pressure monitor of said first safety system by applicationof a progressively variable pressure thereto from an auxiliary source ofpressure higher than that of the normal pressure conditions existing insaid turbine system, restoring said first safety system to service,taking said second safety system out of service while said first safetysystem continues to provide its monitoring functions, testing theoperability of the speed monitor of said second safety system andtesting the operability of the gas flow pressure monitor of said secondsafety system by application of a progressively variable pressurethereto from said auxiliary source of pressure higher than that of thenormal pressure conditions existing in said turbine installation, andfinally restoring said second safety system tO service operation inparallel with said first safety system.